LEDs for General Lighting

LEDs for General Lighting & UV Curing

LEDs for UV Curing Support Performance Price Quality Brand Energy Savings Life Specs Service Vendor Relationship Form Factor Process Control ROI

How do we improve our UV LED selection & application success? LEDs for UV Curing How do we improve our UV LED selection & application success?

Characterizing UV LED Curing Systems UV Output Electrical Input Form Factor Uniformity of Output Use of Optics Product Life Thermal Management and Cooling Ruggedness and Reliability Intended Use & Process Window Understanding UV LED system characteristics drastically improves product selection & application success!

UV Output in Theory Wavelength (nm) - distance between corresponding points of a wave. Peak Irradiance (Watts/cm2) - radiant power arriving at a surface per unit area at a point in time. Energy Density (Joules/cm2) - radiant energy arriving at a surface per unit area over time. It is the integral of irradiance over time. Time Energy Density Irradiance

UV Output in Practice Wavelength (nm) – must be matched to formulation of ink, coating, or adhesive. 395 nm most typically used. 365, 385, and 405 nm also available. 280 nm in development. Peak Irradiance (Watts/cm2) – beneficial for penetration and surface cure. Energy Density (Joules/cm2) – promotes more thorough cure and faster line speed. Time Energy Density Irradiance

UV Output in Practice Formulations need a minimum Peak Irradiance (W/cm2) to react. High Peak Irradiance (W/cm2) doesn’t necessarily mean high Energy Density (J/cm2). New evidence suggests there may be a maximum Peak Irradiance (Watts/cm2) for formulations. High Energy Density (J/cm2) needed for fast line speeds and more thorough cure.

Irradiance vs Distance

Irradiance vs Energy Density Higher Power Lower Total Energy Higher Power Higher Total Energy Lower Power Lower Total Energy Lower Power Higher Total Energy Energy Density

Irradiance vs Energy Density System A is 16 W/cm2 and 20 x 150 mm wide at the emitting window. Irradiance profile measures 2.34 J/cm2 in energy density with 1.2 KW input. A and B deliver similar energy density (area under irradiance curves) but may not cure the chemistry similarly. System B is 8 W/cm2 and 40 x 150 mm wide at the emitting window. Irradiance profile measures 2.53 J/cm2 in energy density with 1.4 KW input.

Nominal Power (Watts/in) Electrical Input vs Irradiance Product Wavelength (nm) Length (mm/in) UV Head DC Supply Power (Watts) Nominal Power (Watts/in) Irradiance (Watts/cm2) LED – FL400 395 450/18 4,361 DC 240 16 5,451 DC 300 20 5,775 DC 320 24 Mercury Broad Band 5,400 AC 1 – 2 7,200 AC 400 2 – 3 9,000 AC 500 3 - 4 10,800 AC 600 4 - 5 *For purposes of comparison, all lamps are 450 mm (18”). **Calculations do not include chillers, exhaust blowers, or make-up air. Strictly a comparison of lamp supply power and output irradiance. ***Irradiance for UV LED curing systems is specified at the emitting window. Conventional UV systems are typically at 2” from lamp head.

Nominal Power (Watts/in) Electrical Input vs Energy Density Product Emitting Window L x W (mm) Irradiance (Watts/cm2) DC Supply (Watts) Nominal Power (Watts/in) Energy Density (Joules/cm2) A 80 x 10 8 145 45 0.56 B 75 x 20 670 225 1.10 C 960 325 D 75 x 40 1400 475 2.40 *For purposes of comparison, all four air-cooled products have flat glass emitting windows and are 395 nm. **Irradiance for UV LED curing systems is specified at the emitting window. ***Energy density measured at same belt speed using an EIT L395 radiometer. Top of radiometer was 5 mm from emitting window. A B C D

Energy Density (J/cm2) Varies Significantly Across Market Offerings Diode Power Design Raw diode selection Diode qty. / packing density Packaging methods Peak irradiance DC power input Driver technology Model variations Cooling effectiveness Window width Quantity of heads Quality Maintenance Uniformity Ingress resistance Amount of degradation over time Quality & consistency of clean room mfg. Chiller & plumbing Air filters Emitting window

Thermal Management & Cooling This is not radiated IR energy but energy created by inefficiencies Approximately 30% to 40% of input power is converted to useable UV output Approximately 60 to 70% of input power is converted to unwanted heat Cannot exceed maximum LED junction temperature Cooling is designed to optimize the efficiency of the LEDs Cooling can be air or liquid

Poor Thermal Management Factors Impact Result Junction and solder joint temps over 110°C Uneven cooling Liquid coolant below 25°C Unsealed heads Affects curing uniformity along length of heads Condensation Foreign matter on LEDs creating hot spots and failures Gradual & catastrophic diode failures Decrease in irradiance & energy density Reduced ability to fully cure & drive press speed

Ruggedness & Reliability Clean room assembly practices Sealed heads Water resistance 20K to 50K lifetime ON hours Robust and cleanable quartz emitting window Impact resistance Cooling systems designed to operate at higher temperatures

Form Factor Smaller lengths scaled end-to-end to cover web Single length heads to span full web width Air-cooled or Liquid-cooled configurations

Form Factor – Scaled Lamps

Intended use drives LED selection, integration, and process window Intended Use & Process Window LEDs AVAILABLE IN CONFIGURATIONS TO SPAN ANY WEB WIDTH OR Trend is towards air-cooled systems Irradiance over 20W/cm2 often unnecessary Air-cooled Up to 20 W/cm2 Water-cooled Up to 50 W/cm2 A PROPERLY CHARACTERIZED UV LED SYSTEM SPECIFIES: Wavelength Energy Density Irradiance W/cm2 Intended use drives LED selection, integration, and process window + + 280 nm in development 365 nm 385 nm 395 nm 405 nm Faster press speeds More thorough cure Major differences across products and vendors A high peak irradiance (W/cm2) DOES NOT guarantee a high energy density (J/cm2). Peak irradiance provides NO insight into delivered energy density

Intended Use & Process Window Physical properties of final cure – drive chemistry formulation Formulation - matched to wavelength and irradiance (Watts/cm2) Working Distance - lamp peak irradiance or head optics selected to deliver needed irradiance at cure surface Process Line Speed – determines needed energy density (Joules/cm2) Plant Environment & Preference - drives cooling selection (air or water) Mounting location – available application space / web width drives lamp form factor Lamp proximity / orientation to unwanted cure surfaces – influences use of optics and shielding

Characterizing UV LED Curing Systems UV Output Electrical Input Form Factor Uniformity of Output Use of Optics Product Life Thermal Management and Cooling Ruggedness and Reliability Intended Use & Process Window Understanding UV LED system characteristics drastically improves product selection & application success!

Thank You! Jennifer Heathcote Phoseon Technology Global Director of Business Development Jennifer.Heathcote@phoseon.com +1 (312) 550-5828 www.phoseon.com

Uniformity of Output Uniformity Improves with web distance from LED Source. Peak irradiance at web decreases with distance.

Optics Flat Glass Rod Lens External Reflector Internal Reflector A single row of LEDs or a narrow matrix of LEDs must be used with optics and reflectors to be effective. Typically results in less energy density.

Optics: Irradiance (Watts/cm2) vs. Energy Density (Joules/cm2) Flat Glass Use of optics can increase peak irradiance above that for flat glass (nominally 100%). But optics are most effective with narrow emitters and typically emit less total energy density.

Over 2 Million hours of total SLM Lifetime Testing LED On-Time UV Intensity 10K 20K 30K 40K 100% 70% LED 90% 80% 50K Conventional Lamps: Replaced every 2,500 hours 70K Hours 60K Over 2 Million hours of total SLM Lifetime Testing